The present invention relates to compounds that are useful as catalyst activator components. More particularly the present invention relates to such compounds that are particularly adapted for use in the polymerization of unsaturated compounds having improved activation efficiency and performance. Such compounds are particularly advantageous for use in a polymerization process wherein catalyst, catalyst activator, and at least one polymerizable monomer are combined under polymerization conditions to form a polymeric product.
It is previously known in the art to activate Ziegler-Natta polymerization catalysts, particularly such catalysts comprising Group 3-10 metal complexes containing delocalized xcfx80-bonded ligand groups, by the use of an activator. Generally in the absence of such an activator compound, also referred to as a cocatalyst, little or no polymerization activity is observed. A class of suitable activators are aluminoxanes, or alkylaluminoxanes, which are generally believed to be oligomeric or polymeric alkylaluminoxy compounds, including cyclic oligomers. The skilled artisan will appreciate that the precise chemical structure of individual alumoxane molecules including methyl alumoxane has eluded full characterization. The structure of methylalumoxane is postulated to consist of linear chains, cyclic rings, or polyhedra, which forms may interconvert in solution. Generally such compounds contain, on average about 1.5 alkyl groups per aluminum atom, and are prepared by reaction of trialkylaluminum compounds or mixtures of compounds with water (Reddy et al, Prog. Poly. Sci., 1995, 20, 309-367). The resulting product is in fact a mixture of various substituted aluminum compounds including especially, trialklyaluminum compounds. The amount of such free trialkylaluminum compound in the mixture generally varies from 1 to 50 percent by weight of the total product. Examples of alumoxanes include methylalumoxane (MAO) made by hydrolysis of trimethylaluminum as well as modified methylalumoxane (MMAO), made by hydrolysis of a mixture of trimethylaluminum and triisobutylaluminum. MMAO advantageously is more soluble in aliphatic solvents than is MAO.
A different type of activator compound is a Bronsted acid salt capable of transferring a proton to form a cationic derivative or other catalytically active derivative of such Group 3-10 metal complex. Preferred Bronsted acid salts are such compounds containing a cation/anion pair that is capable of rendering the Group 3-10 metal complex catalytically active. Suitable activators comprise fluorinated arylborate anions, most preferably, the tetrakis(pentafluorophenyl)borate anion. Additional suitable anions include sterically shielded diboron anions of the formula: 
wherein:
S is hydrogen, alkyl, fluoroalkyl, aryl, or fluoroaryl, ArF is fluoroaryl, and X1 is either hydrogen or halide, disclosed in U.S. Pat. No. 5,447,895.
Examples of preferred charge separated (cation/anion pair) activators are protonated ammonium, sulfonium, or phosphonium salts capable of transferring a hydrogen ion, disclosed in U.S. Pat. Nos. 5,198,401, 5,132,380, 5,470,927, and 5,153,157, as well as oxidizing salts such as carbonium, ferrocenium and silyilium salts, disclosed in U.S. Pat Nos. 5,350,723, 5,189,192 and 5,626,087.
Further suitable activators for the above metal complexes include strong Lewis acids including (trisperfluorophenyl)borane and tris(perfluorobiphenyl)borane. The former composition has been previously disclosed for the above stated end use in EP-A-520,732, and elsewhere, whereas the latter composition is disclosed in Marks, et al., J. Am. Chem. Soc., 118, 12451-12452 (1996). Additional teachings of the foregoing activators may be found in Chen, et al, J. Am. Chem. Soc. 1997, 119, 2582-2583, Jia et al, Organometallics, 1997, 16, 842-857. and Coles et al, J. Am. Chem. Soc. 1997, 119, 8126-8126. All of the foregoing salt and Lewis acid activators in practice are based on perfluorophenyl substituted boron compounds. Although the quantity of such activator compound used is quite low, residual boron and fluorinated benzene values remaining in the polymer may be detrimental to final polymer properties, such as applications requiring high dielectrical properties.
In U.S. Pat. No. 5,453,410, an alumoxane, particularly methylalumoxane, was disclosed for use in combination with cationic constrained geometry metal complexes, especially in a molar ratio of metal complex to alumoxane of from 1/1 to 1/50. This combination beneficially resulted in improved polymerization efficiency. Similarly, in U.S. Pat. Nos. 5,527,929, 5,616,664, 5,470,993, 5,556,928, 5,624,878, various combinations of metal complexes with trispentafluorophenyl boron cocatalyst, and optionally an alumoxane, were disclosed for use as catalyst compositions for olefin polymerization.
In EP-A-719,797, the use of two or more catalyst activators, specifically one or more aluminum compounds, such as aluminum trialkyls or alumoxanes, together with a boron compound, such as trispentafluorophenylborane were disclosed. The resulting polymer products were distinctly bimodal, thereby indicating that the catalyst activators did not interact to form a single, highly active activator differing from either of the initial reagents.
Despite the satisfactory performance of the foregoing catalyst activators under a variety of polymerization conditions, there is still a need for improved cocatalysts for use in the activation of various metal complexes under a variety of reaction conditions. In particular, it is desirable to remove boron containing contaminating compounds from such activator composition. Such boron containing contaminating compounds result primarily from ligand exchange with the alumoxane, and comprise trialkylboron compounds having from 1 to 4 carbons in each alkyl group, for example, trimethylboron, triisobutylboron, or mixed trialkylboron products. It would be desirable if there were provided compounds that could be employed in solution, slurry, gas phase or high pressure polymerizations and under homogeneous or heterogeneous process conditions having improved activation properties, that lack such trialkylboron species.
It is known that an exchange reaction between aluminum trialkyl compounds and tris(perfluorophenyl)borane occurs under certain conditions. This phenomenon has been previously described in U.S. Pat. No. 5,602,269.
According to the present invention there is now provided a composition of matter comprising:
a fluorohydrocarbyl-substituted alumoxane compound corresponding to the formula:
R1xe2x80x94(AIR3O)mxe2x80x94R2,
wherein:
R1 independently each occurrence is a C1-40 aliphatic or aromatic group;
R2 independently each occurrence is a C1-40 aliphatic or aromatic group or in the case of a cyclic oligomer, R1 and R2 together form a covalent bond;
R3 independently each occurrence is a monovalent, fluorinated organic group containing from 1 to 100 carbon atoms or R1, with the proviso that in at least one occurrence per molecule, R3 is a monovalent, fluorinated organic group containing from 1 to 100 carbon atoms, and
m is a number from 1 to 1000.
The composition may exist in the form of mixtures of compounds of the foregoing formula, and further mixtures with a trihydrocarbylaluminum compound, and may exist in the form of linear chains, cyclic rings, or polyhedra, which forms may interconvert in solution.
Additionally according to the present invention there is provided a catalyst composition for polymerization of an ethylenically unsaturated, polymerizable monomer comprising, in combination, the above described combination and a Group 3-10 metal complex, or the reaction product resulting from such combination.
Even further according to the present invention there is provided a process or polymerization of one or more addition polymerizable monomers comprising contacting the same, optionally in the presence of an inert aliphatic, alicyclic or aromatic hydrocarbon, with the above catalyst composition or a supported derivative thereof.
Finally, there is provided a composition comprising the reaction product of an alkylalumoxane and BArf3; wherein:
Arf is a fluorinated aromatic moiety of from 6 to 30 carbon atoms;
the reaction steps comprising contacting the alkylalumoxane and BArf3 under ligand exchange conditions and removing at least a portion of the volatile byproducts.
The foregoing combination is uniquely adapted for use in activation of a variety of metal complexes, especially Group 4 metal complexes, under standard and atypical olefin polymerization conditions. In particular, it is highly desirable for use in polymerization processes in combination with Group 4 metal complexes containing one or two cyclopentadienyl groups (including substituted, multiple ring and partially hydrogenated derivatives thereof) and an inert support to prepare supported catalysts for use in the polymerization of olefins, particularly under gas phase polymerization conditions.
All references herein to elements belonging to a certain Group refer to the Periodic Table of the Elements published and copyrighted by CRC Press, Inc., 1995. Also any reference to the Group or Groups shall be to the Group or Groups as reflected in this Periodic Table of the Elements using the IUPAC system for numbering groups.
The catalyst activators of the invention are readily prepared by combining an alkylalumoxane, which may also contain residual quantities of trialkylaluminum compound, with a fluoroaryl ligand source, preferably a strong Lewis acid containing fluoroaryl ligands, optionally followed by removing byproducts formed by the ligand exchange. The reaction may be performed in a solvent or diluent, or neat, and preferably is performed neat, or in as concentrated solution as possible, for as long reaction time as possible. Intimate contacting of the neat reactants can be effectively achieved by removing volatile components under reduced pressure from a solution of the separate reactants, to form a solid mixture of reactants and, optionally, intermediate exchange products and desired final exchange products, and thereafter, continuing such contacting optionally at an elevated temperature. Preferred fluoroaryl ligand sources are trifluoroarylboron compounds, most preferably tris(pentafluorophenyl)boron, which result in trialkylboron ligand exchange products, that are relatively volatile and easily removable from the reaction mixture, or more preferably, trifluoroarylaluminum compounds. It should be noted that the standard technique of preparation of alkylalumoxanes, for example reaction of a trialkylaluminum compound with water, cannot directly be adapted for use to form the present compositions under industrial conditions, due to thermal instability and reactivity, that is, explosive nature, of trifluoroarylaluminum compounds, especially, tris(pentafluoro)phenylaluminum.
The reactants may be combined in any aliphatic, alicyclic or aromatic liquid diluent or mixture thereof. Preferred are C6-8 aliphatic and alicyclic hydrocarbons and mixtures thereof, including hexane, heptane, cyclohexane, and mixed fractions such as Isopar(trademark) E, available from Exxon Chemicals Inc. Preferably however, the reactants are combined in the absence of a diluent, that is, the neat reactants are merely combined and heated. Preferred contacting times are at least one hour, preferably at least 90 minutes, at a temperature of at least 25xc2x0 C., preferably at least 30xc2x0 C., most preferably at least 35xc2x0 C. Desirably, the contacting is also done prior to addition of a metal complex catalyst, such as a metallocene, in order to avoid formation of further derivatives and multiple metal exchange products having reduced catalytic effectiveness. After contacting of the alkylalumoxane and source of fluoroaryl ligand the reaction mixture may be purified to remove ligand exchange products, especially any trialkylboron compounds by any suitable technique. Alternatively, but less desirably, a Group 3-10 metal complex catalyst may first be combined with the reaction mixture prior to removing the residual ligand exchange products. It will be appreciated by the skilled artisan that the degree of fluoroaryl-substitution of the alumoxane can be controlled over a wide range by manipulating the reaction conditions. Thus, a low degree of fluoroaryl substitution can be achieved by the use of lower temperatures, solvents, and shorter contact times. Conversely, a higher degree of substitution can be achieved by the use of neat reactants, long reaction times, higher temperatures and dynamic removal of volatile byproducts under vacuum. By selecting appropriate reaction conditions, fluoroaryl-substituted alumoxanes having a wide range of properties can be produced which may be tailored to a variety of uses.
Suitable techniques for removing alkyl exchange byproducts from the reaction mixture include degassing optionally at reduced pressures, distillation, solvent exchange, solvent extraction, extraction with a volatile agent, contacting with a zeolite or molecular sieve, and combinations of the foregoing techniques, all of which are conducted according to conventional procedures. The quantity and nature of the residual boron-containing exchange byproducts remaining in of the resulting product may be determined by 11B NMR analysis. Preferably the quantity of residual trialkylboron exchange product is less than 10 weight percent, more preferably less than 1.0 weight percent, most preferably less than 0.1 weight percent, based on fluorohydrocarbyl-substituted alumoxane compound.
As previously mentioned the resulting product contains a quantity of fluorinated organic substituted aluminoxy compound. More particularly, the product may be defined as a composition comprising a mixture of aluminum containing Lewis acids said mixture corresponding to the formula:
[(xe2x80x94AlQ1xe2x80x94Oxe2x80x94)z(xe2x80x94AlArfxe2x80x94Oxe2x80x94)zxe2x80x2](Arfzxe2x80x3Al2Qf6xe2x88x92zxe2x80x3)
where;
Q1 independently each occurrence is selected from C1-20 alkyl;
Arf is a fluorinated aromatic hydrocarbyl moiety of from 6 to 30 carbon atoms;
z is a number from 1 to 50, preferably from 1.5 to 40, more preferably from 2 to 30, and the moiety (xe2x80x94AlQ1xe2x80x94Oxe2x80x94) is a cyclic or linear oligomer with a repeat unit of 2-30;
zxe2x80x2 is a number from 1 to 50, preferably from 1.5 to 40, more preferably from 2 to 30, and the moiety (xe2x80x94AlArfxe2x80x94Oxe2x80x94) is a cyclic or linear oligomer with a repeat unit of 2-30; and
zxe2x80x3 is a number from 0 to 6, and the moiety (Arfzxe2x80x3Al2Q16xe2x88x92zxe2x80x3) is either tri(fluoroarylaluminum), trialkylaluminum, or an adduct of tri(fluoroarylaluminum) with a sub-stoichiometric to super-stoichiometric amount of a trialkylaluminum.
The moieties (Arfzxe2x80x3Al2Q16xe2x88x92zxe2x80x3) may exist as discrete entities or dynamic exchange products. That is, such moieties may be in the form of dimeric or other multiple centered products in combination with metal complexes resulting from partial or complete ligand exchange, especially when combined with other compounds such as metallocenes. Such exchange products may be fluxional in nature, the concentration thereof being dependant on time, temperature, solution concentration and the presence of other species able to stabilize the compounds, thereby preventing or slowing further ligand exchange. Preferably zxe2x80x3 is from 1-5, more preferably from 1-3.
Preferred compositions according to the present invention are those wherein Arf is pentafluorophenyl, and Q1 is C1-4 alkyl. Most preferred compositions according to the present invention are those wherein Ar is pentafluorophenyl, and Q1 each occurrence is methyl, isopropyl or isobutyl.
The present composition is a highly active co-catalyst for use in activation of metal complexes, especially Group 4 metallocenes for the polymerization of olefins. In such use it is desirably employed as a dilute concentration in a hydrocarbon liquid, especially an aliphatic hydrocarbon liquid for use as a homogeneous catalyst activator, especially for solution polymerizations. Additionally, the composition may be deposited on an inert support, especially a particulated metal oxide or polymer, in combination with the metal complex to be activated according to known techniques for producing supported olefin polymerization catalysts, and thereafter used for gas phase or slurry polymerizations.
When in use as a catalyst activator, the molar ratio of metal complex to activator composition is preferably from 0.1:1 to 3:1, more preferably from 0.2:1 to 2:1, most preferably from 0.25:1 to 1:1, based on the metal contents of each component. In most polymerization reactions the molar ratio of metal complex: polymerizable compound employed is from 10xe2x88x9212:1 to 10xe2x88x921:1, more preferably from 10xe2x88x9212:1 to 10xe2x88x925:1.
The reagents employed in the preparation and use of the present compositions, particularly the alumoxane reagent and, where used, the support, should be thoroughly dried prior to use, preferably by heating at 200-500xc2x0 C., optionally under reduced pressure, for a time from 10 minutes to 100 hours. By this procedure the quantity of residual aluminum trialkyl present in the alumoxane is reduced as far as possible.
The support for the activator component may be any inert, particulate material, but most suitably is a metal oxide or mixture of metal oxides, preferably alumina, silica, an aluminosilicate or clay material. Suitable volume average particle sizes of the support are from 1 to 1000 xcexcM, preferably from 10 to 100 xcexcM. Most desired supports are calcined silica, which may be treated prior to use to reduce surface hydroxyl groups thereon, by reaction with a silane, a trialkylaluminum, or similar reactive compound. Any suitable means for incorporating the present composition onto the surface of a support (including the interstices thereof) may be used, including dispersing the cocatalyst in a liquid and contacting the same with the support by slurrying, impregnation, spraying, or coating and thereafter removing the liquid, or by combining the cocatalyst and a support material in dry or paste form and intimately contacting the mixture, thereafter forming a dried, particulated product. In a preferred embodiment, silica is preferably reacted with a tri(C1-10alkyl)aluminum, most preferably, trimethylaluminum, triethylaluminum, triisopropylaluminum or triisobutylaluminum, in an amount from 0.1 to 100, more preferably 0.2 to 10 mmole aluminum/g silica, and thereafter contacted with the above activator composition, or a solution thereof, in a quantity sufficient to provide a supported cocatalyst containing from 0.1 to 1000, preferably from 1 to 500 xcexcmole activator/g silica. The active catalyst composition is prepared by thereafter adding the metal complex or a mixture of metal complexes to be activated to the surface of the support.
Suitable metal complexes for use in combination with the foregoing cocatalysts include any complex of a metal of Groups 3-10 of the Periodic Table of the Elements capable of being activated to polymerize monomers, especially olefins by the present activators. Examples include Group 10 diimine derivatives corresponding to the formula: 
M* is Ni(II) or Pd(II);
Xxe2x80x2 is halo, hydrocarbyl, or hydrocarbyloxy;
Ar* is an aryl group, especially 2,6-diisopropylphenyl or aniline group;
CTxe2x80x94CT is 1,2-ethanediyl, 2,3-butanediyl, or form a fused ring system wherein the two T groups together are a 1,8-naphthanediyl group; and
Axe2x88x92 is the anionic component of the foregoing charge separated activators.
Similar complexes to the foregoing are also disclosed by M. Brookhart, et al., in J. Am. Chem. Soc., 118, 267-268 (1996) and J. Am. Chem. Soc., 117, 6414-6415 (1995), as being active polymerization catalysts especially for polymerization of xcex1-olefins, either alone or in combination with polar comonomers such as vinyl chloride, alkyl acrylates and alkyl methacrylates.
Additional complexes include derivatives of Group 3, 4, or Lanthanide metals containing from 1 to 3 xcfx80-bonded anionic or neutral ligand groups, which may be cyclic or non-cyclic delocalized xcfx80-bonded anionic ligand groups. Exemplary of such xcfx80-bonded anionic ligand groups are conjugated or nonconjugated, cyclic or non-cyclic dienyl groups, allyl groups, boratabenzene groups, and arene groups. By the term xe2x80x9cxcfx80-bondedxe2x80x9d is meant that the ligand group is bonded to the transition metal by a sharing of electrons from a partially delocalized xcfx80-bond.
Each atom in the delocalized xcfx80-bonded group may independently be substituted with a radical selected from the group consisting of hydrogen, halogen, hydrocarbyl, halohydrocarbyl, hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from Group 14 of the Periodic Table of the Elements, and such hydrocarbyl- or hydrocarbyl-substituted metalloid radicals further substituted with a Group 15 or 16 hetero atom containing moiety. Included within the term xe2x80x9chydrocarbylxe2x80x9d are C1-20 straight, branched and cyclic alkyl radicals, C6-20 aromatic radicals, C7-20 alkyl-substituted aromatic radicals, and C7-20 aryl-substituted alkyl radicals. In addition two or more such radicals may together form a fused ring system, including partially or fully hydrogenated fused ring systems, or they may form a metallocycle with the metal. Suitable hydrocarbyl-substituted organometalloid radicals include mono-, di- and tri-substituted organometalloid radicals of Group 14 elements wherein each of the hydrocarbyl groups contains from 1 to 20 carbon atoms. Examples of suitable hydrocarbyl-substituted organometalloid radicals include trimethylsilyl, triethylsilyl, ethyledimethylsilyl, methyldiethylsilyl, triphenylgermyl, and trimethylgermyl groups. Examples of Group 15 or 16 hetero atom containing moieties include amine, phosphine, ether or thioether moieties or divalent derivatives thereof, e.g. amide, phosphide, ether or thioether groups bonded to the transition metal or Lanthanide metal, and bonded to the hydrocarbyl group or to the hydrocarbyl-substituted metalloid containing group.
Examples of suitable anionic, delocalized xcfx80-bonded groups include cyclopentadienyl, indenyl, fluorenyl, tetrahydroindenyl, tetrahydrofluorenyl, octahydrofluorenyl, pentadienyl, cyclohexadienyl, dihydroanthracenyl, hexahydroanthracenyl, decahydroanthracenyl groups, and boratabenzene groups, as well as C1-10 hydrocarbyl-substituted or C1-10 hydrocarbyl-substituted silyl substituted derivatives thereof. Preferred anionic delocalized xcfx80-bonded groups are cyclopentadienyl, pentamethylcyclopentadienyl, tetramethylcyclopentadienyl, tetramethylsilylcyclo-pentadienyl, indenyl, 2,3-dimethylindenyl, fluorenyl, 2-methylindenyl, 2-methyl-4-phenylindenyl, tetrahydrofluorenyl, octahydrofluorenyl, and tetrahydroindenyl.
The boratabenzenes are anionic ligands which are boron containing analogues to benzene. They are previously known in the art having been described by G. Herberich, et al., in Organometallics, 1995, 14, 1, 471-480. Preferred boratabenzenes correspond to the formula: 
wherein Rxe2x80x3 is selected from the group consisting of hydrocarbyl, silyl, or germyl, said Rxe2x80x3 having up to 20 non-hydrogen atoms. In complexes involving divalent derivatives of such delocalized xcfx80-bonded groups one atom thereof is bonded by means of a covalent bond or a covalently bonded divalent group to another atom of the complex thereby forming a bridged system.
Suitable metal complexes for use in the catalysts of the present invention may be derivatives of any transition metal including Lanthanides, but preferably of Group 3, 4, or Lanthanide metals which are in the +2, +3, or +4 formal oxidation state meeting the previously mentioned requirements. Preferred compounds include metal complexes (metallocenes) containing from 1 to 3 xcfx80-bonded anionic ligand groups, which may be cyclic or noncyclic delocalized xcfx80-bonded anionic ligand groups. Exemplary of such xcfx80-bonded anionic ligand groups are conjugated or nonconjugated, cyclic or non-cyclic dienyl groups, allyl groups, and arene groups. By the term xe2x80x9cxcfx80-bondedxe2x80x9d is meant that the ligand group is bonded to the transition metal by means of delocalized electrons present in a xcfx80 bond.
Each atom in the delocalized xcfx80-bonded group may independently be substituted with a radical selected from the group consisting of halogen, hydrocarbyl, halohydrocarbyl, and hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from Group 14 of the Periodic Table of the Elements. Included within the term xe2x80x9chydrocarbylxe2x80x9d are C1-20 straight, branched and cyclic alkyl radicals, C6-20 aromatic radicals, C7-20 alkyl-substituted aromatic radicals, and C7-20 aryl-substituted alkyl radicals. In addition two or more such radicals may together form a fused ring system or a hydrogenated fused ring system. Suitable hydrocarbyl-substituted organometalloid radicals include mono-, di- and trisubstituted organometalloid radicals of Group 14 elements wherein each of the hydrocarbyl groups contains from 1 to 20 carbon atoms. Examples of suitable hydrocarbyl-substituted organometalloid radicals include trimethylsilyl, triethylsilyl, ethyldimethylsilyl, methyldiethylsilyl, triphenylgermyl, and trimethylgermyl groups.
Examples of suitable anionic, delocalized xcfx80-bonded groups include cyclopentadienyl, indenyl, fluorenyl, tetrahydroindenyl, tetrahydrofluorenyl, octahydrofluorenyl, pentadienyl, cyclohexadienyl, dihydroanthracenyl, hexahydroanthracenyl, and decahydroanthracenyl groups, as well as C1-10 hydrocarbyl-substituted derivatives thereof. Preferred anionic delocalized xcfx80-bonded groups are cyclopentadienyl, pentamethylcyclopentadienyl, tetramethylcyclo-pentadienyl, indenyl, 2,3-dimethylindenyl, fluorenyl, 2-methylindenyl and 2-methyl-4-phenylindenyl.
More preferred are metal complexes corresponding to the formula:
LlMXmXxe2x80x2nXxe2x80x3p, or a dimer thereof
wherein:
L is an anionic, delocalized, xcfx80-bonded group that is bound to M, containing up to 50 nonhydrogen atoms, optionally two L groups may be joined together through one or more substituents thereby forming a bridged structure, and further optionally one L may be bound to X through one or more substituents of L;
M is a metal of Group 4 of the Periodic Table of the Elements in the +2, +3 or +4 formal oxidation state;
X is an optional, divalent substituent of up to 50 non-hydrogen atoms that together with L forms a metallocycle with M;
Xxe2x80x2 is an optional neutral Lewis base having up to 20 non-hydrogen atoms;
Xxe2x80x3 each occurrence is a monovalent, anionic moiety having up to 40 non-hydrogen atoms, optionally, two Xxe2x80x3 groups may be covalently bound together forming a divalent dianionic moiety having both valences bound to M, or form a neutral, conjugated or nonconjugated diene that is xcfx80-bonded to M (whereupon M is in the +2 oxidation state), or further optionally one or more Xxe2x80x3 and one or more Xxe2x80x2 groups may be bonded together thereby forming a moiety that is both covalently bound to M and coordinated thereto by means of Lewis base functionality;
l is 1 or 2;
m is 0 or 1;
n is a number from 0 to 3;
p is an integer from 0 to 3; and
the sum, l+m+p, is equal to the formal oxidation state of M.
Such preferred complexes include those containing either one or two L groups. The latter complexes include those containing a bridging group linking the two L groups. Preferred bridging groups are those corresponding to the formula (ER*2)x wherein E is silicon or carbon, R* independently each occurrence is hydrogen or a group selected from silyl, hydrocarbyl, hydrocarbyloxy and combinations thereof, said R* having up to 30 carbon or silicon atoms, and x is 1 to 8. Preferably, R* independently each occurrence is methyl, benzyl, tert-butyl or phenyl.
Examples of the foregoing bis(L) containing complexes are compounds corresponding to the formula: 
wherein:
M is titanium, zirconium or hafnium, preferably zirconium or hafnium, in the +2 or +4 formal oxidation state;
R3 in each occurrence independently is selected from the group consisting of hydrogen, hydrocarbyl, silyl, germyl, cyano, halo and combinations thereof, said R3 having up to 20 non-hydrogen atoms, or adjacent R3 groups together form a divalent derivative (that is, a hydrocarbadiyl, siladiyl or germadiyl group) thereby forming a fused ring system, and
Xxe2x80x3 independently each occurrence is an anionic ligand group of up to 40 nonhydrogen atoms, or two Xxe2x80x3 groups together form a divalent anionic ligand group of up to 40 nonhydrogen atoms or together are a conjugated diene having from 4 to 30 non-hydrogen atoms forming a xcfx80-complex with M, whereupon M is in the +2 formal oxidation state, and
R*, E and x are as previously defined.
The foregoing metal complexes are especially suited for the preparation of polymers having stereoregular molecular structure. In such capacity it is preferred that the complex possess C2 symmetry or possess a chiral, stereorigid structure. Examples of the first type are compounds possessing different delocalized xcfx80-bonded systems, such as one cyclopentadienyl group and one fluorenyl group. Similar systems based on Ti(IV) or Zr(IV) were disclosed for preparation of syndiotactic olefin polymers in Ewen, et al., J. Am. Chem. Soc. 110, 6255-6256 (1980). Examples of chiral structures include bis-indenyl complexes. Similar systems based on Ti(IV) or Zr(IV) were disclosed for preparation of isotactic olefin polymers in Wild et al., J. Organomet. Chem, 232, 233-47, (1982).
Exemplary bridged ligands containing two xcfx80-bonded groups are: (dimethylsilyl-bis-cyclopentadienyl), (dimethylsilyl-bis-methylcyclopentadienyl), (dimethylsily-bis-ethylcyclopentadienyl, (dimethylsilyl-bis-t-butylcyclopentadienyl), (dimethylsilyl-bis-tetramethylcyclopentadienyl), (dimethylsilyl-bis-indenyl), (dimethylsilyl-bis-tetrahydroindenyl), (dimethylsilyl-bis-fluorenyl), (dimethylsilyl-bis-tetrahydrofluorenyl), (dimethylsilyl-bis-2-methyl-4-phenylindenyl), (dimethylsilyl-bis-2-methylindenyl), (dimethylsilyl-cyclopentadienyl-fluorenyl), (1,1,2,2-tetramethyl-1,2-disilyl-bis-cyclopentadienyl), (1,2-bis(cyclopentadienyl)ethane, and (isopropylidene-cyclopentadienyl-fluorenyl).
Preferred Xxe2x80x3 groups are selected from hydride, hydrocarbyl, silyl, germyl, halohydrocarbyl, halosilyl, silylhydrocarbyl and aminohydrocarbyl groups, or two Xxe2x80x3 groups together form a divalent derivative of a conjugated diene or else together they form a neutral, xcfx80-bonded, conjugated diene. Most preferred Xxe2x80x3 groups are C1-20 hydrocarbyl groups.
A further class of metal complexes utilized in the present invention correspond to the formula:
LlMXmXxe2x80x2nXxe2x80x3p, or a dimer thereof
wherein:
L is an anionic, delocalized, xcfx80-bonded group that is bound to M, containing up to 50 nonhydrogen atoms;
M is a metal of Group 4 of the Periodic Table of the Elements in the +2, +3 or +4 formal oxidation state;
X is a divalent substituent of up to 50 non-hydrogen atoms that together with L forms a metallocycle with M;
Xxe2x80x2 is an optional neutral Lewis base ligand having up to 20 non-hydrogen atoms;
Xxe2x80x3 each occurrence is a monovalent, anionic moiety having up to 20 non-hydrogen atoms, optionally two Xxe2x80x3 groups together may form a divalent anionic moiety having both valences bound to M or a neutral C5-30 conjugated diene, and further optionally Xxe2x80x2 and Xxe2x80x3 may be bonded together thereby forming a moiety that is both covalently bound to M and coordinated thereto by means of Lewis base functionality;
l is 1 or 2;
m is 1;
n is a number from 0 to 3;
p is an integer from 1 to 2; and
the sum, l+m+p, is equal to the formal oxidation state of M.
Preferred divalent X substituents preferably include groups containing up to 30 nonhydrogen atoms comprising at least one atom that is oxygen, sulfur, boron or a member of Group 14 of the Periodic Table of the Elements directly attached to the delocalized xcfx80-bonded group, and a different atom, selected from the group consisting of nitrogen, phosphorus, oxygen or sulfur that is covalently bonded to M.
A preferred class of such Group 4 metal coordination complexes used according to the present invention correspond to the formula: 
wherein:
M is titanium or zirconium in the +2 or +4 formal oxidation state;
Rxe2x80x23 in each occurrence independently is selected from the group consisting of hydrogen, hydrocarbyl, silyl, germyl, cyano, halo and combinations thereof, said Rxe2x80x23 having up to 20 non-hydrogen atoms, or adjacent Rxe2x80x23 groups together form a hydrocarbadiyl, siladiyl or germadiyl group thereby forming a fused ring system,
each Xxe2x80x3 is a halo, hydrocarbyl, hydrocarbyloxy or silyl group, said group having up to 20 nonhydrogen atoms, or two Xxe2x80x3 groups together form a C5-30 conjugated diene;
Yxe2x80x2 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NR*xe2x80x94, xe2x80x94PR*xe2x80x94;
Z is SiR*2, CR*2, SiR*2SiR*2, CR*2CR*2, CR*=CR*, CR*2SiR*2, or GeR*2, wherein: R* is as previously defined.
Illustrative Group 4 metal complexes that may be employed in the practice of the present invention include:
cyclopentadienyltitaniumtrimethyl,
cyclopentadienyltitaniumtriethyl,
cyclopentadienyltitaniumtriisopropyl,
cyclopentadienyltitaniumtriphenyl,
cyclopentadienyltitaniumtribenzyl,
cyclopentadienyltitanium-2,4-pentadienyl,
cyclopentadienyltitaniumdimethylmethoxide,
cyclopentadienyltitaniumdimethylchloride,
pentamethylcyclopentadienyltitaniumtrimethyl,
indenyltitaniumtrimethyl,
indenyltitaniumtriethyl,
indenyltitaniumtripropyl,
indenyltitaniumtriphenyl,
tetrahydroindenyltitaniumtribenzyl,
pentamethylcyclopentadienyltitaniumtriisopropyl,
pentamethylcyclopentadienyltitaniumtribenzyl,
pentamethylcyclopentadienyltitaniumdimethylmethoxide,
pentamethylcyclopentadienyltitaniumdimethylchloride,
(xcex75-2,4-dimethyl-1,3-pentadienyl)titaniumtrimethyl,
octahydrofluorenyltitaniumtrimethyl,
tetrahydroindenyltitaniumtrimethyl,
tetrahydrofluorenyltitaniumtrimethyl,
(1,1-dimethyl-2,3,4,9,10-xcex7-1,4,5,6,7,8-hexahydronaphthalenyl)titaniumtrimethyl,
(1,1,2,3-tetramethyl-2,3,4,9,10-xcex7-1,4,5,6,7,8-hexahydronaphthalenyl)titaniumtrimethyl,
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilanetitanium dichloride,
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilanetitanium dimethyl,
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)-1,2-ethanediyltitanium dimethyl,
(tert-butylamido)(hexamethyl-xcex75-indenyl)dimethylsilanetitanium dimethyl,
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilane titanium (III) 2-(dimethylamino)benzyl;
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilanetitanium (III) allyl,
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
(tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
(tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (IV) 1,3-butadiene,
(tert-butylamido)(2,3-dimethylindenyl)dimethyisilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
(tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (IV) 1,3-butadiene,
(tert-butylamido)(2,3-dimethylindenyl)dimethylsilanetitanium (II) 1,3-pentadiene,
(tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (II)1,3-pentadiene,
(tert-butylamido)(2-methylindenyl)dimethylsilanetitanium (IV) dimethyl,
(tert-butylamido)(2-methyl-4-phenylindenyl)dimethylsilanetitanium (II) 1,4-diphenyl-1,3-butadiene,
tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilanetitanium (IV) 1,3-butadiene,
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilanetitanium (II) 1,4-dibenzyl-1,3-butadiene,
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilanetitanium (II) 2,4-hexadiene,
(tert-butylamido)(tetramethyl-xcex75-cyclopentadienyl)dimethylsilanetitanium (II) 3-methyl 1,3-pentadiene,
(tert-butylamido)(2,4-dimethyl-1,3-pentadien-2-yl)dimethylsilanetitaniumdimethyl,
(tert-butylamido)(1,1-dimethyl-2,3,4,9,10-xcex7-1,4,5,6,7,8-hexahydronaphthalen-4-yl)dimethylsilanetitaniu mdimethyl,
(tert-butylamido)(1,1,2,3-tetramethyl-2,3,4,9,10-xcex7-1,4,5,6,7,8-hexahydronaphthalen-4-yl)dimethylsilanetitaniumdimethyl,
(tert-butylamido)(tetramethylcyclopentadienyl)dimethy1silanetitanium 1,3-pentadiene,
(tert-butylamido)(3-(N-pyrrolidinyl)inden-1-yl)dimethylsilanetitanium 1,3-pentadiene,
(tert-butylamido)(2-methyl-s-indacen-1-yl)dimethylsilanetitanium 1,3-pentadiene, and
(tert-butylamido)(3,4-cyclopenta(l)phenanthren-2-yl)dimethylsilanetitanium 1,4-diphenyl-1,3-butadiene.
Bis(L) containing complexes including bridged complexes suitable for use in the present invention include:
biscyclopentadienylzirconiumdimethyl,
biscyclopentadienyltitaniu mdiethyl,
biscyclopentadienyltitaniumdiisopropyl,
biscyclopentadienyltitaniumdiphenyl,
biscyclopentadienylzirconium dibenzyl,
biscyclopentadienyltitanium-2,4-pentadienyl,
biscyclopentadienyltitaniummethylmethoxide,
biscyclopentadienyltitaniummethylchloride,
bispentamethylcyclopentadienyltitaniu mdimethyl,
bisindenyltitaniumdimethyl,
indenylfluorenyltitaniumdiethyl,
bisindenyltitaniummethyl(2-(dimethylamino)benzyl),
bisindenyltitanium methyltrimethylsilyl,
bistetrahydroindenyltitanium methyltrimethylsilyl,
bispentamethylcyclopentadienyltitaniumdiisopropyl,
bispentamethylcyclopentadienyltitaniumdibenzyl,
bispentamethylcyclopentadienyltitaniummethylmethoxide,
bispentamethylcyclopentadienyltitaniummethylchloride,
(dimethylsilyl-bis-cyclopentadienyl)zirconiumdimethyl,
(dimethylsilyl-bis-pentamethylcyclopentadienyl)titanium-2,4-pentadienyl,
(dimethylsilyl-bis-t-butylcyclopentadienyl)zirconiumdichloride,
(methylene-bis-pentamethylcyclopentadienyl)titanium(III) 2-(dimethylamino)benzyl,
(dimethylsilyl-bis-indenyl)zirconiumdichloride,
(dimethylsilyl-bis-2-methylindenyl)zirconiumdimethyl,
(dimethylsilyl-bis-2-methyl-4-phenylindenyl)zirconiumdimethyl,
(dimethylsilyi-bis-2-methylindenyl)zirconium-1,4-diphenyl-1,3-butadiene,
(dimethylsilyl-bis-2-methyl-4-phenylindenyl)zirconium (II) 1,4-diphenyl-1,3-butadiene,
(dimethylsilyl-bis-tetrahydroindenyl)zirconium(II) 1,4-diphenyl-1,3-butadiene,
(dimethylsilyi-bis-fluorenyl)zirconiumdichloride,
(dimethylsilyl-bis-tetrahydrofluorenyl)zirconiumdi(trimethylsilyi),
(isopropylidene)(cyclopentadienyl)(fluorenyl)zirconiumdibenzyl, and
(dimethylsilylpentamethylcyclopentadienylfluorenyl)zirconiu mdimethyl.
Suitable polymerizable monomers include ethylenically unsaturated monomers, acetylenic compounds, conjugated or non-conjugated dienes, and polyenes. Preferred monomers include olefins, for examples alpha-olefins having from 2 to 20,000, preferably from 2 to 20, more preferably from 2 to 8 carbon atoms and combinations of two or more of such alpha-olefins. Particularly suitable alpha-olefins include, for example, ethylene, propylene, 1-butene, 1-pentene, 4-methylpentene-1, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, or combinations thereof, as well as long chain vinyl terminated oligomeric or polymeric reaction products formed during the polymerization, and C10-30 xcex1-olefins specifically added to the reaction mixture in order to produce relatively long chain branches in the resulting polymers. Preferably, the alpha-olefins are ethylene, propene, 1-butene, 4-methyl-pentene-1,1-hexene, 1-octene, and combinations of ethylene and/or propene with one or more of such other alpha-olefins. Other preferred monomers include styrene, halo- or alkyl substituted styrenes, tetrafluoroethylene, vinylcyclobutene, 1,4-hexadiene, dicyclopentadiene, ethylidene norbomene, and 1,7-octadiene. Mixtures of the above-mentioned monomers may also be employed.
In general, the polymerization may be accomplished at conditions well known in the prior art for Ziegler-Natta or Kaminsky-Sinn type polymerization reactions. Examples of such well known polymerization processes are depicted in WO 88/02009, U.S. Pat. Nos. 5,084,534, 5,405,922, 4,588,790, 5,032,652, 4,543,399, 4,564,647, 4,522,987, and elsewhere. Preferred polymerization temperatures are from 0-250xc2x0 C. Preferred polymerization pressures are from atmospheric to 3000 atmospheres.
Molecular weight control agents can be used in combination with the present cocatalysts. Examples of such molecular weight control agents include hydrogen, silanes or other known chain transfer agents. A particular benefit of the use of the present cocatalysts is the ability (depending on reaction conditions) to produce narrow molecular weight distribution xcex1-olefin homopolymers and copolymers in greatly improved cocatalyst efficiencies and purity, especially with respect to residual aluminum containing contaminants. Preferred polymers have Mw/Mn of less than 2.5, more preferably less than 2.3. Such narrow molecular weight distribution polymer products are highly desirable due to improved tensile strength properties.
Gas phase processes for the polymerization of C2-6 olefins, especially the homopolymerization and copolymerization of ethylene and propylene, and the copolymerization of ethylene with C3-6 xcex1-olefins such as, for example, 1-butene, 1-hexene, 4-methyl-1-pentene are well known in the art. Such processes are used commercially on a large scale for the manufacture of high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE) and polypropylene.
The gas phase process employed can be, for example, of the type which employs a mechanically stirred bed or a gas fluidized bed as the polymerization reaction zone. Preferred is the process wherein the polymerization reaction is carried out in a vertical cylindrical polymerization reactor containing a fluidized bed of polymer particles supported above a perforated plate, the fluidization grid, by a flow of fluidization gas.
The gas employed to fluidize the bed comprises the monomer or monomers to be polymerized, and also serves as a heat exchange medium to remove the heat of reaction from the bed. The hot gases emerge from the top of the reactor, normally via a tranquilization zone, also known as a velocity reduction zone, having a wider diameter than the fluidized bed and wherein fine particles entrained in the gas stream have an opportunity to gravitate back into the bed. It can also be advantageous to use a cyclone to remove ultra-fine particles from the hot gas stream. The gas is then normally recycled to the bed by means of a blower or compressor and a one or more heat exchangers to strip the gas of the heat of polymerization.
A preferred method of cooling of the bed, in addition to the cooling provided by the cooled recycle gas, is to feed a volatile liquid to the bed to provide an evaporative cooling effect. The volatile liquid employed in this case can be, for example, a volatile inert liquid, for example, a saturated hydrocarbon having 3 to 8, preferably 4 to 6, carbon atoms. In the case that the monomer or comonomer itself is a volatile liquid, or can be condensed to provide such a liquid this can be suitably be fed to the bed to provide an evaporative cooling effect. Examples of olefin monomers which can be employed in this manner are olefins containing from 3 to eight, preferably from 3 to six carbon atoms. The volatile liquid evaporates in the hot fluidized bed to form gas which mixes with the fluidizing gas. If the volatile liquid is a monomer or comonomer, it will undergo some polymerization in the bed. The evaporated liquid then emerges from the reactor as part of the hot recycle gas, and enters the compression/heat exchange part of the recycle loop. The recycle gas is cooled in the heat exchanger and, if the temperature to which the gas is cooled is below the dew point, liquid will precipitate from the gas. This liquid is desirably recycled continuously to the fluidized bed. It is possible to recycle the precipitated liquid to the bed as liquid droplets carried in the recycle gas stream, as described, for example, in EP-A-89691, U.S. Pat. No. 4,543,399, WO 94/25495 and U.S. Pat. No. 5,352,749, which are hereby incorporated by reference. A particularly preferred method of recycling the liquid to the bed is to separate the liquid from the recycle gas stream and to reinject this liquid directly into the bed, preferably using a method which generates fine droplets of the liquid within the bed. This type of process is described in WO 94/28032, the teachings of which are also hereby incorporated by reference.
The polymerization reaction occurring in the gas fluidized bed is catalyzed by the continuous or semi-continuous addition of catalyst. The catalyst can also be subjected to a prepolymerization step, for example, by polymerizing a small quantity of olefin monomer in a liquid inert diluent, to provide a catalyst composite comprising catalyst particles embedded in olefin polymer particles.
The polymer is produced directly in the fluidized bed by catalyzed (co)polymerization of the monomer(s) on the fluidized particles of catalyst, supported catalyst or prepolymer within the bed. Start-up of the polymerization reaction is achieved using a bed of preformed polymer particles, which, preferably, is similar to the target polyolefin, and conditioning the bed by drying with inert gas or nitrogen prior to introducing the catalyst, the monomer(s) and any other gases which it is desired to have in the recycle gas stream, such as a diluent gas, hydrogen chain transfer agent, or an inert condensable gas when operating in gas phase condensing mode. The produced polymer is discharged continuously or discontinuously from the fluidized bed as desired, optionally exposed to a catalyst kill and optionally pelletized.
Similarly, supported catalysts for use in slurry polymerization may be prepared and used according to previously known techniques. Generally such catalysts are prepared by the same techniques as are employed for making supported catalysts used in gas phase polymerizations. Slurry polymerization conditions generally encompass polymerization of a C2-20 olefin, diolefin, cycloolefin, or mixture thereof in an aliphatic solvent at a temperature below that at which the polymer is readily soluble in the presence of a supported catalyst.